Vertical Installation of an Elongated Process Unit

ABSTRACT

This invention relates to a method for installation of an elongate process unit ( 4 )on the seabed, said process unit ( 4 ) to be handled comprising a first process unit end and a second process unit end. A method of retrieving an elongate process unit ( 4 ) from the seabed is also provided. Further, this invention relates to a receptor apparatus for use in a process unit handling operation, such as a process unit installation or retrieval operation.

This invention relates to a method for installation of an elongateprocess unit on the seabed, said process unit having a first processunit end and a second process unit end. A method of retrieving saidprocess unit from the seabed is also provided. Further, this inventionrelates to a receptor apparatus for use in a process unit handlingoperation.

BACKGROUND OF THE INVENTION

Since the installation or retrieval of a process unit, such as aseparator, can become a part of the IMR-scheme for a field, it isimportant that this operation can be done efficiently with a minimum ofdown time. There is reason to believe that the maximum allowableoperational sea-state for a horizontal deployment will be somewhatlimited especially for operations from a monohull.

Prior Art

U.S. Pat. No. 4,676,696 (Laursen) relates to an apparatus for securing aflowline to a structure near the seabed, comprising a verticallyoriented guide funnel placed atop a guide tube that is provided with ahelical shoulder cooperating with an alignment key mounted on theflowline. During installation, the flowline is stabbed into the guidefunnel and guide tube thereby causing the alignment key to slide alongthe shoulder until a pair of hinge pins mounted on the flowline haveentered into a pair of slots in the wall of the guide tube.Subsequently, the flowline is hinged down to a horizontal position.

U.S. Pat. No. 4,671,702 (Langner) relates to a method and apparatus forconnecting a flowline to a subsea structure. A riser and flowlineconnection tool are deployed downwardly to the subsea structure and aflowline terminal head, which is at the end of the flowline, is pulledto the flowline connection tool by means of a pullcable. Then theflowline terminal head is secured to the subsea structure and theflowline connection tool is recovered to the surface. The flowlineterminal head consists of a connector hub with clamping surface to whichthe flowline is welded, and a flexible carrier pipe of interlockingmetallic rings into which the end of the flowline is inserted. Thecarrier pipe limits the curvature of the flowline as the terminal headis bent into alignment with a flowline receptacle of the subseastructure. The flowline terminal head may include buoyant encirclingrings which keep it free of difficult terrain in the vicinity of thesubsea structure.

U.S. Pat. No. 4,277,202 (Archambaud et al.) relates to a method and anapparatus for deploying and connecting an end of an underwater flowlineto a connecting sleeve.

U.S. Pat. No. 4,877,356 (Bontenbal) concerns a method and an apparatusfor stabbing a flowline into a guide tube near the waterbottom andsubsequently hinging over the flowline to a horizontal position. Theconnection operation is facilitated by a vertically oriented guide tubehaving along the inner wall thereof a pair of parallel slots whichprovide at the lower ends thereof pivot supports on which a pair ofpivots which are mounted near the lower end of the flowline land duringthe stab in procedure. Deflectors are provided for deflecting a lowerportion of the flowline while the pivots are lowered through the slotsso as to induce the flowline to obtain a curved shape into apredetermined direction before the pivots land onto the pivot supports.

U.S. Pat. No. 4,676,696 and U.S. Pat. No. 4,717,287 (Laursen) bothrelate to an apparatus for securing a flowline to a structure near theseabed comprises a vertically oriented guide funnel placed atop a guidetube that is provided with a helical shoulder cooperating with analignment key mounted on the flowline. During installation the flowlineis stabbed into the guide funnel and guide tube thereby causing thealignment key to slide along the shoulder until a pair of hinge pinsmounted on the flowline have entered into a pair of slots in the wall ofthe guide tube. Subsequently the flowline is hinged down to a horizontalposition.

The above documents all describe methods and apparatuses for deployingflowlines or risers, whereas the methods and apparatus according to thisinvention relates to handling process units, in particular elongateprocess equipment such as separators, heat exchangers, containers,pumps, vessels, tanks or the like. The receptor apparatuses according tothe above documents are all arranged for receiving an end of a flowlinesection while deploying a flowline on or near the seabed. Thus, they arenot constructed for receiving the much larger load from processequipment.

On the other hand, the receptor apparatus according to this invention isdesigned for receiving such process units, e.g., separators, heatexchangers, containers or the like, in particular elongate processunits, and the load such process units exert on the receptor apparatus.

SHORT SUMMARY OF THE INVENTION

This invention provides a method for installation of an elongate processunit on the seabed, in which said process unit has a first process unitend and a second process unit end. Said method is characterized in thatit comprises the following steps.

-   a) preparing and moving said process unit to a position in which it    is ready for being launched from a vessel and lowered through the    sea with its longitudinal axis in a generally vertical orientation;-   b) launching said process unit from said vessel;-   c) lowering said process unit through the sea surface, the splash    zone and further down to a deployment site on the seabed;-   d) after said process unit lowering step c), entering said first    process unit end into a receptor device for said first process unit    end, so as to temporarily form a lower end of said first process    unit end, the receptor device being located on the seabed or on a    module foundation for said process unit at the seabed;-   e) completing said process unit entry in said receptor device and    retaining said first process unit end in place in said receptor    device; and-   f) lowering said second process unit end so as to bring the process    unit (4) to a generally horizontal orientation on the seabed or said    module foundation for said process unit, said first process unit end    remaining supported by said receptor device, so as to form a fulcrum    for said first process unit end, thus facilitating lowering of said    second process unit end, and-   g) deploying said process unit at the deployment site.

Furthermore, this invention provides a method of retrieving an elongateprocess unit from the seabed, in which said process unit has a firstprocess unit end and a second process unit end. Said method ischaracterized in that it comprises the following steps:

-   a) preparing said process unit for removal from a deployment site;-   b) lifting said second process unit end from the seabed or from on a    module foundation for said process unit, said first process unit end    being retained in a receptor device, thus temporarily forming a    lower end of said first process unit end, and so as to bring the    longitudinal axis of said process unit to a generally vertical    orientation; said first process unit end of said process unit and    said receptor device forming a fulcrum for said first process unit    end, thus facilitating lifting of said second process unit end;-   c) disengaging said first process unit end from said receptor    device;-   d) hauling said process unit from said deployment site at the    seabed, up through the sea, the splash zone and the sea surface to a    vessel;-   e) bringing said process unit aboard said vessel, and-   g) preparing and moving said process unit to a generally horizontal    position onboard said vessel, in which it is sea-fastened and ready    for being transported on said vessel.

Moreover, this invention provides a receptor apparatus for use in aprocess unit handling operation, in which the process unit to be handledcomprises a first process unit end and a second process unit end. Saidreceptor apparatus is characterized in that it comprises a receptordevice arranged for receiving and engaging a first process unit end, andfurther arranged for receiving and supporting the load of said processunit, Said receptor device is arranged for receiving and engaging saidfirst process unit end, and said receptor device is further arranged forretaining said first process unit end in position in said receptordevice so as to provide a fulcrum for said first process unit end duringhandling of said second process unit end.

More features and advantages of said method for lowering and deployingsaid process unit, of said method for retrieving said process unit, andof said receptor apparatus according to the invention appear from therespective, accompanying dependent claims.

SHORT DESCRIPTION OF THE DRAWINGS

The following drawings serves to illustrate some embodiments accordingto the invention. The drawings are not made to scale.

FIG. 1 a is a schematic sectional side view of a lower portion of theprocess unit to be lowered and introduced into a receptor according tothe invention.

FIG. 1 b is a corresponding schematic sectional side view of a lowerportion of the process unit which has been lowered into a position inthe receptor device according to the invention, and now could be furtherarranged onto the module foundation of the desired deployment site.

FIG. 2 a is a schematic top view of a vessel from which the process unitinstallation operation according to one embodiment of the inventtionwill take place. The process unit has been positioned on the vessel deckin a position to be launched.

FIG. 2 b is a schematic and partly sectional side view of the processunit being launched over a vessel stern roller of the vessel.

FIG. 2 c shows a schematic and partly sectional view of the process unitready to be lowered into the receptor device at the deployment site.

FIG. 2 d shows a schematic and partly sectional view similar to FIG. 2 cof the process unit in which process unit entry into the receptor devicehas been completed, and now being ready to be further lowered onto themodule foundation of the deployment site.

FIG. 2 e shows a schematic and partly sectional view similar to FIGS. 2c-2 d of the process unit being deployed onto the module foundation ofthe deployment site.

FIG. 2 f shows a schematic and cross sectional view of the process unitthrough line A-A shown in FIG. 2 e.

FIG. 3 a is a schematic side view of a further embodiment of theinvention in which the process unit is raised into a vertical positionon board the deployment vessel. A receptor device is utilized forkeeping control on the first process unit end while lifting the otherprocess unit end, so as to prepare the launching step of the processunit installation operation. An important advantage of this embodimentof the invention is better control the process unit movements during thelifting step.

FIG. 3 b is a schematic and cross sectional view of the process unitshown in FIG. 3 a, taken along line A-A shown in FIG. 3 a.

FIG. 3 c is a schematic side view similar to FIG. 3 a, in which theprocess unit has been raised to an upright position on the receptordevice.

FIG. 3 d is a schematic side view similar to FIG. 3 a and 3 b, in whichthe first process unit end has been lifted from the receptor device.

FIG. 4 a-f shows schematic and partly sectional views of severallowering and deployment stages of the process unit installationoperation according to the second embodiment of the invention, similarto FIG. 2 a-2 f. The process unit is positioned onto the receptor devicesimilarly to FIGS. 2 a-2 f, but in this embodiment, two shafts areprovided which are located opposed to each other at the first processunit end. Each shaft is introduced into a guide in a bracket so as toform support bearings for the process unit in the receptor device.

FIG. 5 is a schematic and side view similar to FIG. 3 a-3 d, in whichthe first process unit end supported by a receptor device arrangement asindicated in FIGS. 4 a-4 f, and in which lifting of the second processunit end so as to prepare the launching step of the process unitinstallation operation.

FIG. 6 a is a schematic and side view of a process unit, in anembodiment according to the invention in which the framework on thefirst process unit end includes two mating pins located diametricallyopposed to each other and protruding outwards from the side wall of theprocess unit. The two mating pins are each retained in a receptorbracket with a guide for the mating pin.

FIG. 6 b is a schematic and cross sectional view of the process unitshown in FIG. 6 a, taken along line A-A.

FIG. 6 c is a schematic top view of the process unit shown in FIGS. 6a-6 b.

The invention will now be described in more detail, with reference tothe accompanying drawings. The drawings should not be interpreted aslimiting for the scope of the invention, which should be limited by theaccompanying claims only.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Reference is made to FIGS. 2 a-f, and to FIGS. 4 a-f, in which a methodis illustrated for lowering and deploying an elongate process unit 4having a first process unit end 4 a and a second process unit end 4 b onthe seabed. Said elongate process unit 4 may be any process equipment,such as a pump, a tank, a vessel, a container, a heat exchanger or aseparator, e.g., a horizontal gravitational separator. The longitudinallength L of said process unit 4 is generally larger than its crosssectional length, or width, W.

Conducting the lowering and deploying operation with said elongateprocess unit arranged in a generally vertical or upright manner is acentral feature of the invention.

A general embodiment of the process unit lowering and deploying methodwill now be described.

-   a) Said process unit 4 is prepared and moved to a position in which    it is ready for being launched from a vessel 24 and lowered through    the sea with its longitudinal axis in a generally vertical    orientation.-   b) Said process unit 4 is launched from said vessel 24.-   c) Said process unit 4 is lowered into the sea through the sea    surface, the splash zone and further down to a deployment site at    the seabed.-   d) After said process unit lowering step c), entering said first    process unit end 4 a into a receptor device 1 for said first process    unit end 4 a, so as to temporarily form a lower end of said first    process unit end 4 a. Said receptor device 1 may be located on the    seabed or on a module foundation 12 for said process unit 4 at the    seabed.-   e) Then said process unit entry in said receptor device 1 is    completed. Said first process unit end 4 a of said process unit 4 is    retained in place in said receptor device 1.-   f) Said second process unit end 4 b is then lowered so as to bring    the process unit 4 to a generally horizontal orientation on the    seabed or on said module foundation 12 for said process unit 4, said    first process unit end 4 a remaining supported by said receptor    device 1, so as to form a fulcrum for said first process unit end 4    a, thus facilitating lowering of said second process unit end 4 b.-   g) Said process unit 4 is deployed at the deployment site.

Said method may also include the step of landing said process unit 4onto the vessel 24, e.g. onto the deck 14 of the vessel 24 or onto atransport frame 13, and transporting said process unit 4 to an offshoredeployment site.

Said process unit 4 may include one or more, preferably two, launchbeams 5 for facilitating generally horizontal movement of said processunit 4 and for providing support for said process unit 4 on saidsupporting arrangement 12 a, or a process subsea skid 23, or on atransport frame 13.

For transport of said process unit 4 to the deployment site, saidprocess unit 4 may for example be arranged on said launch beams 5 or ona transport frame 13. In the former case, said process unit 4 is movedfrom said transport frame 13 to a vessel deck 14 on said vessel 24 whenpreparing said process unit 4 for launch into the sea. When preparingsaid process unit 4 for lift into the sea by crane, said process unit 4,which may be resting on said transport frame 13, is moved to said vesseldeck 14.

During the whole handling process, keeping control of said process unit4 is very important. Control of said process unit 4 may be kept by meansof a vessel wire system 36. Said vessel wire system includes adeployment crane wire 19 or a lowering wire 19 extending from saidvessel crane or vessel winch 31 on said vessel 24 to said second processunit end 4 b.

When preparing said process unit 4 for launch into the sea, said processunit 4 may be moved and guided towards the stem end of said vessel 24.Said first process unit end 4 a may face said stern end of said vessel24, so that said first process unit end 4 a can be launched into the seafirst. Launch of said process unit 4 may take place over a stern roller29 located at said stern end of said vessel 24.

Said wire system 36 on said vessel 24 may include one or more,preferably two launch wires 22, each extending from said vessel crane orvessel winch 31 via a snatch block 25 or similar for each launch wire 22to an attachment location on said vessel. Said snatch block 25 ispreferably being located at the stern end of said vessel 24. Further,said wire system 36 on said vessel 24 may include a launch control-wirebridle 20 retaining said process unit 4 to a heave compensator 37. Forlowering of said process unit 4, a lowering wire 19 attached to saidvessel crane or vessel winch 31 and extending to said second processunit end 4 b of said process unit 4 may also be included.

During preparation of said process unit 4 for launch into the sea fromsaid transport frame 13 on said vessel deck 14 by means of lowering wire19, said process unit 4 may be brought to a generally vertical positionby lifting said second process unit end 4 b, then disengaging said firstprocess unit end 4 a, hauling said process unit 4 from said transportframe 13, and bringing it into the sea.

When lowering said process unit 4, said vessel 24 is positionedgenerally above said receptor device 1 in the sea, and then said processunit 4 is lowered in the sea with its longitudinal axis in a generallyvertical orientation down to said receptor device 1.

When said process unit 4 has been lowered to the deployment site at theseabed, said process unit 4 may be guided to said receptor device 1before entering said first process unit end 4 a of said process unit 4into said receptor device 1.

A framework 34 including one or more process unit mating pins 6 may beattached to said first process unit end 4 a of said process unit 4, sothat said first process unit end 4 a is guided into engagement with saidreceptor device 1 by means of said one or more process unit mating pins6 being brought into egagement with said receptor device 1.

Said first process unit end is then entered into said receptor device 1.In order to retain said first process unit end 4 a of said process unit4 safely in position in said receptor device 1, said process unit 4 maybe retained in place by means of a lock pin 11, so as to retain said oneor more process unit mating pins 6 included in said framework 34attached to said first process unit end 4 a of said process unit 4 insaid receptor device 1. Said lock pin 11 can be retained in place andoperated in any possible manner, such as being manually operated.However, in a preferred embodiment it is spring loaded and ROVreleasable.

After process unit entry in said receptor device 1, said vessel 24 isthen positioned so that the weight of said process unit 4 is graduallytransferred to said lowering wire 19, so as to start lowering of saidsecond process unit end 4 b towards the seabed or said module foundation12 about said fulcrum formed by said first process unit end 4 a engagingsaid receptor device 1. When the lowering process for said secondprocess unit end 4 b has started, said vessel 24 is moved to a positionso that an axial force component of the tension generated by saidprocess unit 4 in said lowering wire 19 is directed towards saidreceptor device 1. The vessel 24 is arranged so that said axial forcecomponent is generally parallel with the longitudinal, central axis ofsaid process unit 4; and so that transversal force components of saidtension in said lowering wire 19 from said second process unit end 4 bof said process unit 4 to said vessel 24 are reduced or minimized.

Thus, said first process unit end 4 a is retained in engagement withsaid receptor device 1, and the risk of disengagement of said firstprocess unit end 4 a from said receptor device 1 is reduced orminimized.

After said process unit 4 has been deployed onto the seabed or saidmodule foundation 12, said receptor device 1 may be loosened or removedfrom said first process unit end 4 a of said process unit 4.

A receptor apparatus is also provided with this invention for use in aprocess unit handling operation, for example as a process unitinstallation operation as described herein, in which the process unit 4to be handled comprises a first process unit end 4 a and a secondprocess unit end 4 b.

Said receptor apparatus includes a receptor device 1 which is arrangedfor receiving and engaging a first process unit end 4 a, and whichfurther is arranged for receiving and engaging said first process unitend 4 a of said process unit 4, so as to support the load of saidprocess unit 4, and so as to retain said first process unit end 4 a inposition in said receptor device 1, thus providing a fulcrum for saidfirst process unit end 4 a during handling of said second process unitend 4 b.

Said receptor device may be arranged directly on the seabed, but it ispreferably arranged on a module foundation 12. A process subsea skid 23,arranged for supporting said receptor device 1 and the load from saidprocess unit 4 may also be arranged on said module foundation 12.

A framework 34 may be attached to said first process unit end 4 a ofsaid process unit 4. Said framework 34 may include one or more separatormating pins 6. In such cases, said receptor device 1 may be arranged forreceiving said one or more process unit mating pins 6 included in aframework 34 being attached to said first process unit end 4 a of saidprocess unit 4. FIGS. 1 a-1 b, 2 a-2 f, 3 a-3 d and 5 show a processunit 4 with a framework 34 having one mating pin 6, and FIGS. 4 a-4 fand FIGS. 6 a-6 c show a process unit having a framework having twomating pins 6.

In one preferred embodiment according to the invention of said receptorapparatus, said receptor device 1 comprises two or more receptorbrackets 27 in a spaced apart arrangement, each receptor bracket 27having a receptor bracket guide 28. Said receptor bracket guides 28included in said receptor brackets 27 may each be arranged for receivinga process unit mating pin 6 included in said framework 34 attached tosaid first process unit end 4 a, so that said receptor brackets 27 formsupport bearings for said process unit 4 via said process unit matingpins 6 when engaged with said first process unit end 4 a of said processunit 4. Thus, said receptor brackets may form a fulcrum for said firstprocess unit end 4 a of said process unit 4. An elastomeric pad 7 may bearranged in connection with each receptor bracket 27 for dampening theimpact and the load of said process unit 4.

In a second preferred embodiment according to the invention of saidreceptor apparatus, said receptor device 1 includes a receptor 1 aarranged for receiving and engaging a first process unit end 4 a of aprocess unit 4 and a receptor cylinder 9 in connection with saidreceptor 1 a, said receptor cylinder 9 arranged for receiving andengaging said first process unit end 4 b. A receptor dampening oryielding member 8 located in said receptor cylinder 9; said receptordampening member 8 being arranged for receiving the load of said processunit 4 and for dampening or minimizing the impact of the load of saidprocess unit 4 by said first process unit end 4 b on said receptordevice 1. Said receptor dampening member 8 can for example be made of anelastomeric material, it can be a piston dampened by water hydraulic, acoil spring, or any other kind of dampening member. A further adequatealternative could be water hydraulic dampening of said separator 4. Saidreceptor 1 a and said receptor cylinder 9 are supported by two or morereceptor bearings 2 in a spaced apart arrangement on said modulefoundation 12. Said receptor bearings 2 are arranged for receiving andsupporting the load of said process unit 4, and each receptor bearing 2is provided with a receptor rotating pin 3 so as to form a fulcrum forsaid receptor device 1.

Each receptor bearing 2 may also be provided with a dampening pad 7, soas to dampen the impact when said receptor device 1 receives and engagesthe load of said process unit 4 and for assisting said dampening member8 in said receptor device 1 in receiving and supporting this load. Thedampening pad 7 may, e.g., be made of an elastomeric material.

A restraining device 35 can be provided for maintaining a generallyvertical position of said receptor device 1 during entry of said firstprocess unit end 4 a of said process unit 4. Said restraining device 35may be releasable, and is arranged to be released prior to lowering saidprocess unit onto said support arrangement 12 a.

In the cases in which a framework 34 having one or more separator pins 6is attached to said first process unit end 4 a of said process unit 4,said receptor 1 and said receptor cylinder 9 may be arranged forreceiving said process unit mating pin 6 of said framework 34.

For better guidance and engagement of said process unit 4 with saidreceptor apparatus, said receptor cylinder 9 can be provided with arotational guide 10 a arranged for engaging a corresponding shoulder 10b on said process unit mating pin 6, so as to facilitate rotation ofsaid process unit mating pin 6 in said receptor cylinder 9 in order toline up said process unit 4 along said module foundation 12.

After landing of process unit 4 on said module foundation 12, one ormore, preferably two, pairs of alignment devices 26 may be provided foralignment of said process unit 4 onto said module foundation 12.Subsequently, said process unit 4 may be locked onto said modulefoundation 12 by means of a locking pin 32

A receptor apparatus according to the invention may be located at theseabed, preferably on a module foundation at the seabed, and arrangedfor facilitating installation of a process unit 4 at the seabed or forretrieval of a process unit from the seabed. It is also possible tolocate said receptor apparatus on said transport frame 13 on said vessel24, said receptor apparatus being arranged for facilitating transport ofsaid process unit 4 to the offshore deployment site, lifting of saidprocess unit 4 into the sea, or for lifting from the sea and transportof said process unit 4 on said vessel 24 to a desired location, such asthe shore.

In an embodiment according to the invention in which a receptorapparatus including a receptor device 1 is arranged on said vessel 24,it is preferably arranged for assisting in lifting said process unit 4from a position in which its longitudinal axis is oriented in agenerally horizontal direction on said vessel 24, to a position in whichits longitudinal axis is oriented in a generally vertical directionbefore launch or overboarding of said process unit 4. The preparing andmoving step a and launching step may in such cases include the stepsdescribed as follows:

-   Entering said first process unit end into said receptor device 1 for    said first process unit end 4 a so that said first process unit end    4 a engages said receptor device 1, so as to temporarily form a    lower end of said first process unit end 4 a.-   Completing said process unit entry in said receptor device 1 and    retaining said first process unit end 4 a in place in said receptor    device 1, so as to form a fulcrum for said first process unit end 4    a.-   Lifting said second process unit end 4 a while said first process    unit end 4 a remains supported by said receptor device 1, thus    facilitating lifting of said second process unit end 4 b so as to    bring the longitudinal axis of said process unit 4 to a generally    vertical orientation.-   Moving said process unit 4 in said generally vertical orientation to    a position in which it is ready to be launched into the sea; and-   Launching said process unit 4 with its longitudinal axis in a    generally vertical orientation into the sea.    In this case, said installation method may also include the step of    transporting said process unit 4 on said transport frame 13 on said    vessel 24 to the offshore site.

There is also provided a method for retrieving an elongate process unit4 from the seabed, in which said process unit 4 has a first process unitend 4 a and a second process unit end 4 b. A very general embodimentaccording to the invention of such a method may comprise the followingsteps:

-   a) preparing said process unit 4 for removal from a deployment site;-   b) lifting said second process unit end 4 b from the seabed or from    a module foundation 12 for said process unit 4, said first process    unit end 4 a being retained in a receptor device 1, thus temporarily    forming a lower end of said first process unit end 4 a, and so as to    bring the longitudinal axis of said process unit 4 to a generally    vertical orientation; said first process unit end 4 a of said    process unit 4 and said receptor device 1 forming a fulcrum for said    first process unit end 4 a, thus facilitating lifting of said second    process unit end 4 b;-   c) disengaging said first process unit end 4 a from said receptor    device 1;-   d) hauling said process unit 4 from said deployment site at the    seabed, up through the sea, the splash zone and the sea surface to a    vessel 24;-   e) bringing said process unit 4 aboard said vessel 24, and-   g) preparing and moving said process unit 4) to a generally    horizontal position onboard said vessel, in which it is sea-fastened    and ready for being transported on said vessel 24.

Said method may also comprise the step of transporting said process unit4 onboard said vessel 24 for subsequent lift-off.

A receptor apparatus according to the invention may be used for handlingof said first process unit end 4 a of said process unit 4 so as tofacilitate preparation aboard a vessel 24 for launch of said processunit 4 into the sea, but also for handling of said first process unitend 4 a of said process unit 4 so as to facilitate preparation of saidprocess unit 4 aboard a vessel 24 for transport of said process unit 4.

Further, said receptor apparatus according to the invention may be usedfor handling of said first process unit end 4 a of said process unit 4for deployment of said process unit 4 onto said module foundation 12arranged at a deployment site at the seabed, but also for handling ofsaid first process unit end 4 a of process unit 4 for removal of saidprocess unit 4 from said module foundation 12 arranged at a deploymentsite at the seabed.

It is possible to use a receptor apparatus according to the invention inan operation for lowering and deploying said process unit 4 onto adeployment site on the seabed. A further possibility is to use of areceptor apparatus according to the invention in an operation forremoving and hauling said process unit 4 away from a deployment site atthe seabed.

The receptor apparatus with transport frame according to the inventionmay be attached to the process-unit already in the workshop, where theprocess unit is manufactured or assembled, and loaded onto a flatbed ofa lorry, truck, railway carriage or other wheel carriage. Thereby theunit with transport frame may be transported in one piece from theworkshop to the vessel. This will facilitate the handling of the processunit already from the workshop. After retrieval the process-unit withreceptor and transport frame may be loaded onto a lorry, truck, railwaycarriage or other wheel carriage and transported in one piece back tothe workshop for service.

In a preferred embodiment of the invention, the process unit 4 to behandled is a horizontal gravitational separator 4.

Description of a Possible Embodiment of the Invention, in Which SaidProcess Unit is, e.g., a Separator

Since the installation or retrieval of a process unit, such as aseparator, can become a part of the IMR-scheme for a field, it isimportant that this operation can be done efficiently with a minimum ofdown time. There is reason to believe that the maximum allowableoperational sea-state for a horizontal deployment will be somewhatlimited especially for operations from a monohull.

In order to achieve a controllable operation, a central mating pin 6 hasbeen fixed to the framework 34, for example a framework orseparator-skirt 34 located at the first separator end 4 a.

For the lift-option the pin is arranged in a guide-funnel which ispivoting in a base structure situated on a common transport skid 13.This skid is sea-fastened on the vessel deck 14.

The separator 4 is resting on cradles 15 on the transport skid 13 andalso locked to said skid 13. A pad-eye 33 is arranged on the separator 4in the opposite end of the mating pin 6. A ROV-shackle 18 with slingsfrom the crane-hook can be connected hereon for the deployment.

For the launching/hauling option the separator may be resting on thevessel deck by means of two launching beams which may be attached to theseparator by welding, and further sea-fastened to the vessel deck 14.

Separator overboarding may take place for example by crane or bylaunching. FIGS. 3 a-3 d relate to the case of crane overboarding. InFIG. 3 a, the separator 4, resting with its saddles 16 on the cradles 15located on the transport skid 13 situated on the crane vessel deck 14,is in FIG. 3 a shown to be ready for upending by the vessel-crane. Theskid 13 is sea-fastened while the separator 4 is unlocked from the skid13. In FIG. 3 b, the separator, while still resting in the bearings 2 ofthe guide-funnel 1, has been rotated about 90 degrees into the verticalposition in the bearings 2 under fall control by the crane and theguide-funnel 1. When ready to deploy the separator 4, the mating pin 6is unlocked from the guide-funnel 1 and free to be lifted off by thecrane. In FIG. 3 c, the separator is lifted off the guide-funnel 2 andready to be deployed overboard with the crane. FIG. 3 d shows a crosssection of the separator in FIG. 3 a.

By Launching:

Reference is now made to FIGS. 2 a-2 f and to FIGS. 4 a-4 f. Analternative deployment operation can be to launch the separator 4 by,e.g., a 500 ton winch 31 over the stern-roller 29 on the deck 14 of anAHV, as shown in FIGS. 2 a-2 b and 4 a-4 b.

The separator 4 can be fitted with two launch beams 5 similar to what isused for launching large suction anchors of similar size as thisseparator 4. The separator 4 with the launching beams 5 are sea-fastenedto the deck 14 of the vessel 24 during the transport to field.

In addition to the winch lowering wire 19, two launch wires 22 and onelaunch control wire with bridle 20 and associated auxiliary winches arerequired in this embodiment of said launching operation.

FIGS. 2 a and 4 a shows the separator 4 rested on deck 14 ready riggedup for launching.

FIGS. 2 b and 4 b shows the separator 4 being launched over the sternroller 29 by means of a set of winches and launch control wires 22 forsubsequent deployment to seabed by the separate lowering wire 19. Thiswire 19 is connected by shackle 18 to the end of the separator and isheave compensated.

In the case in which the receptor apparatus comprises an entry funnel,separator landing on seabed can be made as follows. A similar pivotedguide funnel 1 as on the transport skid 13 is located on the base frame12,23 subsea. The funnel 1 a will be pointing upward prior to mating toreceive one or more mating pins 6 on the end of the separator in FIG. 2c. The separator 4 is suspended in a preferably heave compensateddeployment wire 19 from a crane or winch 31.

A combined operation of vessel 24 and ROV will assist with aligning themating pin 6 with the funnel 1 a with subsequent lowering and entry intothe funnel 1 within a 90 degrees sector of the latter, as shown in FIG.2 d. An alternative approach is to use two clump weights as proposed forthe base frame 12,12 a, 23.

The funnel cylinder 9 may be fitted with rotational guides 10 a, such ashelical groove-slots, which in conjunction with associatedcontrol-upsets 10 b on the lower end of the mating pin 6 is forcing theseparator to twist the necessary angle during the mating in order toalign correctly on the base. In the bottom of the funnel-cylinder 9 islocated a dampening mechanism 8 which can be of a water hydraulic orelastomeric design, the latter is indicated in the figures.

When landed, the ROV will activate a locking pin locking the separator 4to the guide funnel 1 a. The 90 degrees rotating of the separator ontothe process skid 23 can then start by vessel 24 offsetting and loweringof the deployment wire 19 in AHC (active heave compensation) mode.

The separator saddles 16 will then land in the cradles 15 on the skid23, as shown in FIGS. 2 e and 4 e and the shackle 18, which can be a ROVoperated shackle, will be disconnected by the ROV.

For proper alignment of the separator one or more, preferably twoscrew-adjustable wedge-assemblies 26 underneath the separator areactivated by the ROV. Elastomeric pads 7 underneath the funnel-bearings2 will then allow the separator 4 to be aligned as required on thewedges 26. A ROV activated locking pin 32 underneath the separator 4will then lock it to the process skid 23.

Separator retrieval from seabed can be made as follows. For retrieval ofthe separator 4 from the process-skid 23, the operation will have to bereverted. After all pipe- and cable-connections have been disconnectedby ROV, the ROV-shackle 18 from the crane-hook will then be connected upto the separator 4. The separator is then unlocked and rotated 90degrees into vertical position by the AHC deployment wire 19. Whenmating-pin 6 has been released by the ROV, the separator 4 can beretrieved.

The separator 4 can be brought onto vessel deck 14 either by crane or byhauling, for example as follows.

For retrieval of a lift installed separator from the sea onto the deckby crane, the operation as illustrated in FIGS. 3 a-3 c will bereverted. Prior to lift the separator 4 out of water the ROV willconnect up two tugger lines 30 to the separator to enable to control itover the deck 14 of the vessel 24 and during entry into the guide-funnel1.

For retrieval of a launched separator from the sea onto the deck byhauling, the launch operation shown in FIG. 2 a-2 b can be reverted, andthe separator 4 with launch beams 5 can be sea fastened to deck 14. Thecontrol wire and bridle 20 will be connected and used for the haulingover the stern roller 29 and the lowering wire 19 used for stabilisingfuring the hauling operation.

Advantages of the Invention in IMR (Installation Module Retrieval)Operations

The above upending-operation of the separator will provide someadditional advantages, thus making the IMR-operations more efficient:the upending of the process unit 4 will give a better opportunity topurge and clear the process unit more efficiently for hydrocarbon gasesprior to a retrieval operation. It also provides an improved opportunityfor sand removal at the seabed instead of having to retrieve theseparator to surface for sand-removal if this is the case.

List of Reference Numerals

-   1 receptor device-   1 a receptor-   2 receptor bearing, e.g., funnel bearing-   3 receptor rotating pin, e.g., funnel rotating pin-   4 elongate process unit-   4 a a first process unit end-   4 b a second process unit end-   5 launch beam-   6 process unit mating pin-   7 dampening pad-   8 dampening member-   8 a dampening member, compressed-   8 b dampening member, extended-   9 receptor cylinder, e.g., funnel cylinder-   10 a rotational guide-   10 b guide formation on said process unit mating pin 6 corresponding    to rotational guide 10 a in said receptor cylinder 9-   11 spring loaded lock pin ROV releasable-   12 module foundation-   13 transport frame-   14 vessel deck-   15 guide or cradle-   16 process unit saddle-   17 process unit locking pin/bucket-   18 shackle for deployment wire-   19 lowering wire-   20 launch control-wire bridle-   22 launch wire-   23 process subsea skid-   24 vessel (AHV)-   25 snatch-block for launch-wire-   26 ROV-adjustable wedge for process unit alignment-   27 receptor bracket, e.g., funnel bracket-   28 receptor bracket guide, e.g., funnel bracket guide-   29 stern roller-   30 tugger line-   31 vessel crane or vessel winch-   32 process unit fastening pin, e.g., process unit locking pin-   33 pad-eye-   34 framework-   35 restraining device-   36 vessel wire system-   37 heave compensator

1. A method for installation of an elongate process unit on the seabed,in which said process unit has a first process unit end and a secondprocess unit end, characterized in that said method comprises thefollowing steps: a) preparing and moving said process unit to a positionin which it is ready for being launched from a vessel and loweredthrough the sea with its longitudinal axis in a generally verticalorientation; b) launching said process unit from said vessel; c)lowering said process unit through the sea surface, the splash zone andfurther down to a deployment site at the seabed; d) after said processunit lowering step c), entering said first process unit end into areceptor device for said first process unit end, so as to temporarilyform a lower end of said first process unit end, the receptor devicebeing located on the seabed or on a module foundation for said processunit at the seabed; e) completing said process unit entry in saidreceptor device and retaining said first process unit end in place insaid receptor device; and f) lowering said second process unit end so asto bring the process unit as a whole from the generally verticalorientation to a generally horizontal orientation on the seabed or onsaid module foundation for said process unit, said first process unitend remaining supported by said receptor device, so as to form a fulcrumfor said first process unit end, thus facilitating lowering of saidsecond process unit end, and g) deploying said process unit at thedeployment site.
 2. Method according to claim 1, characterized in thatsaid process unit entry step d) further comprises the step of: guidingsaid process unit to said receptor device before entering said firstprocess unit end of said process unit into said receptor device. 3.Method according to claim 1, characterized in that said preparation andmoving step a) and said launching step b) further include the followingsteps: moving and guiding said process unit towards the stern end ofsaid vessel, said first process unit end facing said stern end of saidvessel; launching said first process unit end over a stern rollerlocated at said stern end of said vessel.
 4. Method according to claim3, characterized in that said process unit moving and guiding step isaccomplished by conveying said process unit to said stern end of saidvessel by means of a vessel crane or vessel winch, preferably having aheave compensator, the vessel crane or vessel winch controlling a vesselwire system which is attached to said process unit, so as to safelyretain and guide said process unit.
 5. Method according to claim 1,characterized in that a receptor device is arranged on said vessel, andthat said preparation and moving step a) and said launching step b)further include the following steps: entering said first process unitend into said receptor device for said first process unit end so thatsaid first process unit end engages said receptor device, so as totemporarily form a lower end of said first process unit end; completingsaid process unit entry in said receptor device and retaining said firstprocess unit end in place in said receptor device, so as to form afulcrum for said first process unit end; lifting said second processunit end while said first process unit end remains supported by saidreceptor device, thus facilitating lifting of said second process unitend so as to bring the longitudinal axis of said process unit to agenerally vertical orientation; moving said process unit in saidgenerally vertical orientation to a position in which it is ready to belaunched into the sea; and launching said process unit with itslongitudinal axis in a generally vertical orientation into the sea. 6.Method according to claim 1, characterized in that said preparing andmoving step a) further comprises the step of: transferring said processunit from a transport frame to a vessel deck on said vessel.
 7. Methodaccording to claim 1, characterized in that a framework including one ormore process unit mating pins is attached to said first process unit endof said process unit, so that said process unit entry step d) furtherincludes the following step: guiding said first process unit end intoengagement with said receptor device by means of said one or moreprocess unit mating pins being brought into engagement with saidreceptor device.
 8. Method according to claim 1, characterized in thatsaid process unit includes at least two launch beams for facilitatinggenerally horizontal movement of said process unit and for providingsupport for said process unit on the seabed, on said module foundation,on a process subsea skid, said vessel deck, or on said transport frameon said vessel deck.
 9. Method according to claim 1, characterized inthat said completing and retaining step e) further includes thefollowing step: locking and retaining said first process unit end ofsaid process unit in place in said receptor device by means of a lockpin, so as to retain said one or more process unit mating pins includedin said frame-work attached said first process unit end of said processunit in said receptor device; said lock pin preferably being springloaded and ROV releasable.
 10. Method according to claim 1,characterized in that said method further comprises the step of: keepingcontrol of said second process unit end of said process unit by means ofsaid vessel wire system including a lowering wire from said vessel craneor vessel winch on said vessel; said process unit lowering step c)further includes the step of positioning said vessel generally abovesaid receptor device in the sea and lowering said process unit in thesea with its longitudinal axis in a generally vertical orientation downto said receptor device; said process unit end lowering step f) furtherincludes the step of positioning said vessel so that the weight of saidprocess unit is gradually transferred to said lowering wire, so as tostart lowering of said second process unit end towards the seabed orsaid module foundation about said fulcrum formed by said first processunit end engaging said receptor device, moving said vessel to a positionso that an axial force component of the tension generated by saidprocess unit in said lowering wire is directed towards said receptordevice; so that said axial force component is generally parallel withthe longitudinal, central axis of said process unit; and so thattransversal force components of said force in said lowering wire fromsaid second process unit end of said process unit to said vessel arereduced or minimized; thus retaining said first process unit end inengagement with said receptor device, and reducing or minimizing therisk of disengagement of said first process unit end from said receptordevice.
 11. Method according to claim 1, characterized in that saidprocess subsea skid, or said transport frame or similar, includes guideand cradle arranged for supporting the load of said process unit to saidmodule foundation or said transport frame; one or more, preferably twopairs of wedges being adjustable in order to align said process unit onsaid process subsea skid or said transport frame, so as to bring thelongitudinal axis of said process unit to the generally same level assaid receptor device engaging said first process unit end of saidprocess unit, thus relieving the load of said process unit from saidreceptor device to the module foundation; and that said process unit 4includes a process unit saddle arranged for transferring the load ofsaid process unit to said guide and cradle.
 12. Method according toclaim 1, characterized in that said wire system on said vessel includesone or more launch wires, extending from said vessel winch or a separatewinch via a snatch block for each launch wire to an attachment locationon said vessel; said snatch block being located at the stern end of saidvessel; a launch control-wire with bridle connected to a separate winch;a lowering wire connected to a separate winch and to said second processunit end of said process unit.
 13. Method according to claim 1,characterized in that after the deployment step g), it further comprisesthe step of: h) loosening or removing said receptor device from saidfirst process unit end.
 14. Method according to claim 1, characterizedin that said elongate process unit is a horizontal gravitationalseparator.
 15. Method according to claim 1, characterized in before saidpreparation and moving step a) and said launching step b): placing areceptor device, including a transport frame, with the process unit inengagement with said receptor device on the flatbed of a lorry, truck,railway carriage or other wheel carriage, transporting said receptordevice with said process unit to said vessel, and lifting said receptordevice with said process unit onto said vessel.
 16. A method ofretrieving an elongate process unit from the seabed, in which saidprocess unit has a first process unit end and a second process unit end,characterized in that said method comprises the following steps: a)preparing said process unit for removal from a deployment site; b)lifting said second process unit end from the seabed or from a modulefoundation for said process unit, said first process unit end beingretained in a receptor device, thus temporarily forming a lower end ofsaid first process unit end, and so as to bring the longitudinal axis ofsaid process unit as a whole from the generally horizontal orientationto a generally vertical orientation; said first process unit end of saidprocess unit and said receptor device forming a fulcrum for said firstprocess unit end, thus facilitating lifting of said second process unitend; c) disengaging said first process unit end from said receptordevice; d) hauling said process unit from said deployment site at theseabed, up through the sea, the splash zone and the sea surface to avessel; e) bringing said process unit aboard said vessel, and g)preparing and moving said process unit to a generally horizontalposition onboard said vessel, in which it is sea-fastened and ready forbeing transported on said vessel.
 17. Receptor apparatus for use in aprocess unit handling operation, in which the process unit to be handledcomprises a first process unit end and a second process unit end,characterized by the following features: a receptor device arranged forreceiving and engaging a first process unit end, and further arrangedfor receiving and supporting the load of said process unit, and saidreceptor device being arranged for receiving and engaging said firstprocess unit end, and said receptor device further being arranged forretaining said first process unit end in place in said receptor deviceand providing a fulcrum for said first process unit end during handlingof said second process unit end and being adapted to take up asubstantial part of the weight of the process unit when the process unitas a whole is transferred between a substantially vertical position anda substantially horizontal position.
 18. Receptor apparatus for use in aprocess handling operation, in which the process unit to be handledcomprises a first process unit end and a second process unit end,characterized by the following features: a receptor device arranged forreceiving and engaging a first process unit end, and further arrangedfor receiving and supporting the load of said process unit, saidreceptor device being arranged for receiving and engaging said firstprocess unit end, and said receptor device further being arranged forretaining said first process unit end in place in said receptor deviceand providing fulcrum for said first process unit end during handling ofsaid second process unit end and being adapted to take up a substantialpart of the weight of the process unit when the process unit as a wholeis transferred between a substantially vertical position and asubstantially horizontal position, said receptor device comprises two ormore receptor brackets in a space apart arrangement, each receptorbracket having a receptor bracket guide; and that said receptor bracketguides included in said receptor brackets are each arranged forreceiving a process unit mating pin included in said framework which isattached to said first process unit end, so that said receptor bracketsform support bearings for said process unit via said process unit matingpins when engaged with said first process unit end of said process unit;thus forming a fulcrum for said first process unit end of said processunit.
 19. Receptor apparatus for use in a process unit handlingoperation, in which the process unit to be handled comprises a firstprocess unit end and a second process unit end, characterized by thefollowing features: a receptor device arranged for receiving andengaging a first process unit end, and further arranged for receivingand supporting the load of said process unit, said receptor device beingarranged for receiving and engaging said first process unit end, andsaid receptor device further being arranged for retaining said firstprocess unit end in place in said receptor device and providing afulcrum for said first process unit end during handling of said secondprocess unit end and being adapted to take up a substantial part of theweight of the process unit when the process unit as a whole istransferred between a substantially vertical position and asubstantially horizontal position, a receptor cylinder in connectionwith said receptor, said receptor cylinder arranged for receiving andengaging said first process unit end, two or more receptor bearings in aspaced apart arrangement for supporting the load of said process unit;each receptor bearing being provided with a receptor rotating pin so asto form a fulcrum for said receptor device. said receptor and saidreceptor cylinder being arranged for receiving a process unit mating pinattached to said first process unit end of said process unit. 20.Receptor apparatus according to claim 17, characterized in that saidreceptor device is arranged on a module foundation arranged forsupporting said receptor device and the load from said process unit. 21.Receptor apparatus according to claim 17, characterized in that saidreceptor device is arranged for receiving one or more process unitmating pins included in a framework being attached to said first processunit end of said process unit.
 22. Receptor apparatus according to claim21, characterized in that said receptor device comprises two or morereceptor brackets in a spaced apart arrangement, each receptor brackethaving a receptor bracket guide; and that said receptor bracket guidesincluded in said receptor brackets are each arranged for receiving aprocess unit mating pin included in said framework which is attached tosaid first process unit end, so that said receptor brackets form supportbearings for said process unit via said process unit mating pins whenengaged with said first process unit end of said process unit; thusforming a fulcrum for said first process unit end of said process unit.23. Receptor apparatus according to claim 17, characterized in that saidreceptor device comprises a receptor arranged for receiving and engaginga first process unit end of a process unit, a receptor cylinder inconnection with said receptor, said receptor cylinder arranged forreceiving and engaging said first process unit end, a receptor dampeningor yielding member located in said receptor cylinder; said receptordampening member being arranged for receiving the load of said processunit and for dampening or minimizing the impact of the load of saidprocess unit by said first process unit end on said receptor device, twoor more receptor bearings in a spaced apart arrangement on said modulefoundation; said receptor bearings being arranged for supporting theload of said process unit; each receptor bearing being provided with areceptor rotating pin so as to form a fulcrum for said receptor device,each receptor bearing optionally being provided with a dampening pad, soas to dampen the impact when said receptor device receives and engagesthe load of said process unit and for assisting said dampening member insaid receptor device in receiving and supporting this load, saidreceptor and said receptor cylinder preferably being arranged forreceiving a process unit mating pin of a framework attached to saidfirst process unit end of said process unit.
 24. Receptor apparatusaccording to claim 23, characterized in that said receptor cylinder isprovided with a rotational guide arranged for engaging a correspondingguide formation or shoulder on said process unit mating pin, so as tofacilitate rotation of said process unit mating pin in said receptorcylinder.
 25. Receptor apparatus according to claim 17 characterized inthat it is located at the seabed, preferably on a module foundation atthe seabed, and arranged for facilitating deployment or removal of aprocess unit on the seabed, or that it is located on said vessel andarranged for facilitating launching of said process unit into the sea,for loading onto said vessel and for transport of said process unit onsaid vessel.
 26. Use of a receptor apparatus according to claim 17comprising handling of said first process unit end of said process unitso as to facilitate preparation aboard a vessel for launch of saidprocess unit into the sea, or handling of said first process unit end ofsaid process unit so as to facilitate preparation of said process unitaboard a vessel for transport of said process unit; or handling of saidfirst process unit end of said process unit for deployment of saidprocess unit onto said module foundation arranged at a deployment siteat the seabed, or handling of said first process unit end of processunit for removal of said process unit from said module foundationarranged at a deployment site at the seabed.